By Janet Raloff
Since 1979, a mysterious epidemic has been afflicting house cats. Feline hyperthyroidism, usually characterized by weight loss, hyperactivity, and eventual heart disease, is now the leading hormonal disorder in cats. A pilot study tentatively links it to certain flame retardants that began showing up in the environment in 1979 and are now ubiquitous.
The chemicals, called polybrominated diphenyl ethers (PBDEs), show up in water, fish, house dust, human foods, and people (SN: 10/25/03, p. 266).
Veterinarian Janice A. Dye of the Environmental Protection Agency in Research Triangle Park, N.C., realized that indoor cats—already known to be at high risk of hyperthyroidism—consume a lot of dust when they groom themselves. Data have suggested that sick cats are also more likely than healthy felines to have eaten canned cat food, especially fish varieties.
Dye’s team tested blood samples from 23 cats, including 11 with hyperthyroidism. Although all carried PBDEs, the animals with the thyroid disease had higher average concentrations. Sick cats and well cats also had different mixes of PBDEs, the researchers report in the Sept. 15 Environmental Science & Technology.
Tests of 20 types of dry and wet cat foods showed that all contained PBDEs, although canned, fish-flavored food had the highest amounts and could deliver 12 times as much of the chemicals as dry foods typically did. The canned, fish-flavored foods also had concentrations of PBDEs that were up to 100 times as high as those in the human diet.
“It sure as heck looks like there’s something going on,” says coauthor Linda S. Birnbaum of EPA. “Our data beg for additional studies.”
